Type of radiation

DOE-HDBK-1130-98

Module 2 Biological Effects

Instructor's Notes

Type of radiation

For example, internally deposited alpha emitters are

more damaging than beta or gamma emitters for the

same energy deposited.

Area of the body that receives a dose

In general, the larger the area of the body that

receives a dose, the greater the biological effect.

Extremities are less sensitive than blood forming and

other critical organs. That is why the annual dose

limit for extremities is higher than for a whole body

dose that irradiates internal organs.

Cell sensitivity

The most sensitive cells are those that are rapidly

dividing. Examples include blood cells, hair follicles,

and the cells lining the gastrointestinal tract.

Individual sensitivity

Some individuals are more sensitive to environmental

factors such as ionizing radiation.

The developing embryo/fetus is the most sensitive,

and children are more sensitive than adults.

In general, the human body becomes relatively less

sensitive to ionizing radiation with increasing age.

The exception is that elderly people are more

sensitive than middle-aged adults due to the inability

to repair damage as quickly (less efficient cell repair

mechanisms).